<div class="doc-item" id="doc-1531"><h2 class="doc-item-name">io!<span class="namespace">(clojure.core)</span></h2><p class="macro">Macro</p><ul class="var-arglists"><li>(<span class="var-name">io!</span> &amp; body)</li></ul><div class="var-docstring"><p>If an io! block occurs in a transaction, throws an
  IllegalStateException, else runs body in an implicit do. If the
  first expression in body is a literal string, will use that as the
  exception message.</p></div><div class="var-source"><pre>; clojure/core.clj:1405
(defmacro io!
  [&amp; body]
  (let [message (when (string? (first body)) (first body))
        body (if message (next body) body)]
    `(if (clojure.lang.LockingTransaction/isRunning)
       (throw (new IllegalStateException ~(or message &quot;I/O in transaction&quot;)))
       (do ~@body))))</pre></div><div class="license"><p>Copyright (c) Rich Hickey. All rights reserved.</p><p>The use and distribution terms for this software are covered by the <a href="http://opensource.org/licenses/eclipse-1.0.php">Eclipse Public License 1.0</a>, which can be found in the file
          epl-v10.html at the root of this distribution. By using this software
          in any fashion, you are agreeing to be bound by the terms of this 
          license. You must not remove this notice, or any other, from this 
          software.</p></div></div>